Improvement in screw-taps



UNITED STATES PATENT OFFICE.

JAMES HOWELL ANDDAVID BIRDSALL, ,OF JERSEY CITY, JERSEY.

IMPROVEMENT IN SCREW-TAPS.

Specification forming o f Letters Patent No. 4 l,509, dated February 9, 1864.

To aZZ whom it may'concern:

Be it known that we, JAMES HOWELL and DAVID BIRDSALL, both of Jersey Gity,in the county of Hudson and State of New Jersey, have invented a new and useful Improvement in Screw-Taps and we do hereby declare that the following is a full, clear', and exact description of the same,retlrence being h-ad to the-accompanying drawings, forming a part of this specilication, in which- Figure l is a longitudinal view of a tap constructed according to our invention. p Fig.l 24is a similar view with the movable head in l section. Fig. 3 isan end view ofthe same.

spouding parts in the several figures. l'

The object of our invention is to prot-ide for Similar letters of reference indicate correthe tapping simultaneously of twoopposite holes in the two tube-sheets of a boiler, or in any other two pieces of metal or other materialatany distance apart in such maunerthat 'tle threads in the said holes shall be true to 'acommon axis, so that a pipe o'i't other piece maybe screwed simultaneously into both; and Ato this end it consists in a tap with two heads, one "or both of which are made adjustable lengthwise of the shaft ofthe tap to bring them at the requisite distance apart; also, in an arrangement of portions of the tap, for the reception of two wrenches, in such manner that in the tapping ot' the two holes simultaneously the shaft may not het, subject:l to torsion. i i Toenabie others skilled in the irrt to make and use our invention, we will proceed toldescribe its construction and operation.

f, "A is the shaft vof the tap, of any length,

@and B G are the heads, which Nmay both be A.movable on the shaft, though it will gener-r ally be only necessary to make one movable. The head B is represented Aas made in'l the same piece with the shaft, and therefore fixed;

and the other, U, is represented'as movable lengthwise of the shaft. The shaft is fur nished with a longitudinal feather, afro tit a groovey in the head G, for the purpose of pre- Venting itfrom turning independently of the shaft and head B, and causing both heads to turn together. The head C is iittedwith a set-screw, b, 'to secure it to the shaft at any required distance from B, according tothe distance apart of the tube-sheets orother pieces to be tapped, the length of the sl'iaft being sutcently greater than the distance between' i the outer faces of the said tube-sheets or other pieces to allow one wrench to be placed on a squared or flattened portion, o, 0f the shaft, outside of the head B, and another wrench to be placed upon a square 'or flattened portion, d, of the head C, outside of the threaded portion thereof, the two squares or flattened portions having their dat surfaces on the same side of the tap. The head U shouldl 4he so much larger than. the fixed head B that the hole in which it will cut'a thread will belarge enough to allow the xed head B to pass through freely without cutting.

The operation of the tap is as follows: The movable head O having been adjusted at a proper distance from the fixed head, according to the distance apart ofthe plates or other pieces to be tapped, so that the twoheads will enter their respective holes together, the head B and the shaft are passed through thc largerhole, which the head C is to tap, and both tapsl arenentered into their respective holes. A

wrench is tlieuapplied ont-hc square or dat e, and another on lthe square or dat d, the

arms of the two wrenches standing in corre- -1 spending directions, and the two wrenches,j are then turned simultaneously in the samedirection, the persons operating 'ehem taking care to operate together to avoid any torsion of the shaft to which, owing to its length, itA

would otherwisevbe liable. The' two heads then cut the threads in" their respective :holes simultaneously, and in so doing each serves as a guide to keep the axis of the othervperpendicular to the surfaces of the plates or pieces to be tapped-or, in' other words, both out their threads true to a 'common axis.

What we claim as ourinvention, and desire to secure by LettersPatent, is-

1. A screw-taphaving two heads,^one o both ot' which are adjustable lengthwise ot' the shaft to bring the two at any required distance apart to tap simultaneously 'two opposite holes in two tube-sheets or other pieces at any distance apart true to a common axis, substantially as herein specitied.

2. Making such a double-headed tap with twov squares or flattened portions for the re- -ception of wrenches, one of said portions being upon the shaft and the other upon the more distant movable head,subs'tan`tially as herein described, to prevent the 4torsion ofthe shaft.

JAMES HOWELL. DAVID BIRDSALL. Witnesses:

D. ROBERTSON, Taos. S. J. DOUGLAS. 

